This invention relates to compounds and methods for treating prostaglandin E mediated diseases, and certain pharmaceutical compositions thereof. More particularly, the compounds of the invention are structurally different from NSAIDs and opiates, and are antagonists of the pain and inflammatory effects of E-type prostaglandins.
Two review articles describe the characterization and therapeutic relevance of the prostanoid receptors as well as the most commonly used selective agonists and antagonists: Eicosanoids From Biotecnology to Therapeutic Applications, Folco, Samuelsson, Maclouf, and Velo eds, Plenum Press, New York, 1996, chap. 14, 137-154 and Journal of Lipid Mediators and Cell Signalling, 1996, 14, 83-87. An article from The British Journal of Pharmacology (1994, 112, 735-740) suggests that Prostaglandin E2 (PGE2) exerts allodynia through the EP1 receptor subtype and hyperalgesia through EP2 and EP3 receptors in the mouse spinal cord.
Thus, selective prostaglandin ligands, agonists or antagonists, depending on which prostaglandin E receptor subtype is being considered, have anti-inflammatory, antipyretic and analgesic properties similar to a conventional non-steroidal anti-inflammatory drug, and in addition, inhibit hormone-induced uterine contractions and have anti-cancer effects. These compounds have a diminished ability to induce some of the mechanism-based side effects of NSAIDs which are indiscriminate cyclooxygenase inhibitors. In particular, the compounds have a reduced potential for gastrointestinal toxicity, a reduced potential for renal side effects, a reduced effect on bleeding times and a lessened ability to induce asthma attacks in aspirin-sensitive asthmatic subjects.
In The American Physiological Society (1994, 267, R289-R-294), studies suggest that PGE2-induced hyperthermia in the rat is mediated predominantly through the EP1 receptor. World patent applications WO 96/06822 (Mar. 7, 1996), WO 96/11902 (Apr. 25, 1996) and EP 752421-A1 (Jan. 08, 1997) disclose compounds as being useful in the treatment of prostaglandin mediated diseases.